Planet Found in Nearest Star System to Earth

Source: European Southern Observatory (ESO)

European astronomers have discovered a planet with about the mass of the Earth orbiting a star in the Alpha Centauri system — the nearest to Earth. It is also the lightest exoplanet ever discovered around a star like the Sun. The planet was detected using the HARPS instrument on the 3.6-metre telescope at ESO’s La Silla Observatory in Chile. The results will appear online in the journal Nature on 17 October 2012.

Alpha Centauri is one of the brightest stars in the southern skies and is the nearest stellar system to our Solar System — only 4.3 light-years away. It is actually a triple star — a system consisting of two stars similar to the Sun orbiting close to each other, designated Alpha Centauri A and B, and a more distant and faint red component known as Proxima Centauri . Since the nineteenth century astronomers have speculated about planets orbiting these bodies, the closest possible abodes for life beyond the Solar System, but searches of increasing precision had revealed nothing. Until now.

“Our observations extended over more than four years using the HARPS instrument and have revealed a tiny, but real, signal from a planet orbiting Alpha Centauri B every 3.2 days,” says Xavier Dumusque (Geneva Observatory, Switzerland and Centro de Astrofisica da Universidade do Porto, Portugal), lead author of the paper. “It’s an extraordinary discovery and it has pushed our technique to the limit!”

54. LOL

6. For a few decades, particularly within the last 20 years, there have been orgs seriously planning

With this announcement, it provides a much-needed boost to their efforts. We now have a real target that really is within our reach. There are several different approaches to propulsion that could get probes to the Centauri systems within Human lifespans (the general target is 100 years between launch and arrival) versus many centuries to get to any of the other exoplanets that have been confirmed thus far. Humanity really needed there to be something in that star system, because short of exotic non-Newtonian drives, the gulf between the stars is much too great.

46. I'm not even sanguine that humans will land on Mars by 2040 given all the technical problems.

47. Who said anything about humans?

It would be unnecessarily difficult and dangerous to send people. What we need to explore space is robots. Even sending people to Mars is a pointless waste of time, effort, and invites a completely avoidable tragedy.

7. 5th paragraph says 6mil km, which is a LOT closer in than Mercury is here, but where there's one...

13. This is Intriguing Because It's Close Enough

that it might eventually be feasible to send a probe, even if it would take a while. But the triple star system just doesn't seem the best environment for maintaing a stable earth-like orbit over the several billions of years necessary for life to develop.

42. But what if the planet doesn't rotate around its axis?

The side facing Alpha Cen B would be continually hot. The other side would have a 72 hour day/night cycle as the planet rotates around Alpha Cen B, exposing itself to light from Alpha Cen A. The distance between Alpha Cen A and B varies over 80 years and Alpha Cen A is 150% the brightness of Sol. Stranger things have happened.

12. I know what you mean, there are a LOT of red dwarfs close by that are invisible to the naked eye.

17. What are the odds? Pretty much zero. There are exotic proposals for colonizing Mercury...

Having mobile platforms riding rails that circumscribe the planet, keeping the colony forever on the nightside away from the sun. I suppose that if Bb's surface isn't molten being so close to its parent star, that could be feasible in the distant future.

"We can send an interstellar probe at speeds approaching the speed of light." You are painfully misinformed there, painful because God if only we did have that capability. No, the ion drives of which you speak are incredibly weak compared to what's needed to even remotely come close to a significant fraction of the speed of light. 0.1c is probably the best we can hope for anytime in the next few centuries (short of other more exotic drives) so at best at those speeds, 40 years one-way.

18. Nope. No Ion drive either. Boom boom boom! Proven since 1958

21. Well, no, we DO have ion drives that have already been used for 4 deep space missions so far...

And while it's a novel approach, you are never going to see nukes being detonated to launch payloads into orbit. That proposal was from a time when people had picnics on hillsides overlooking nuke tests. Yeah, no. Not happening. Perhaps they'll be used well-outside LEO, and it'd be a great way to eliminate our weapons stockpiles, but there are less dangerous approaches that show better potential in the long-run.

24. In the long run

Nuclear pulse propulsion is the only thing that we have right now that will work. If they launched tomorrow and reached 10% of c we'd get to Alpha Centauri by the time I was oh..... 76 years old :p

And yeah I'm willing to risk a few (and it really is a FEW, not a few hundred or few thousand) cancer deaths to do it. Launch the bugger from Antarctica and off we go. But yes, sadly politics destroyed our only idea that will work right now (or any time in the near future) for interstellar travel.

81. I am not an engineer, but I had an idea not sure if it will work

With a much smaller scaled down design inside that otherwise works exactly the same.

Dump the small probe when you get into the Alpha Centauri system and slow the little one down... you would need a lot less fuel to slow down a small probe... the large probe keeps going at 0.1c...

Also do you really have to slow down at the halfway point? I thought the larger issue was if you want to slow down you need to use half your fuel to speed up and half to slow down. If you are carrying the probe plus a bunch of fuel (bombs) that extra mass is what is going to slow things down... not the fact that you have to "slow down at the halfway point".

I know you would need some significant time to slow down without destroying the probe though :p

23. Rail gun would be better.

19. The continuous thrust technology is key to high speeds at this point.

I know our first efforts are local but if we were going to build something to go there it would be boosted to get it going and the last stage would push it at nearly as fast as the thrust exits which right now uses xenon propellant ions but we could do a Tim Allen on it.

My point is,...we could do it with what we already know. Ion drive could travel at nearly the speed of light in open space.

22. Your ethusiasm for ion drives is wonderful, but sadly Einstein is having none of it...

E=MC^2 pretty much precludes the possibility of ion drives getting us to the stars faster than a space snail's pace. The fuel requirements and the mass of that fuel grows exponentially the faster you go. Again, there are different proposals that are fairly exotic but are seriously being looked into and show some promise. Ion drives are firmly in the realm of Newtonian physics and thus are completely subject to that equation. Hopefully the other proposals pan out.

26. "fuel requirements and the mass of that fuel grows exponentially the faster you go"

No, actually, the fuel stays the same over relative time as the speed increases since there is zero resistance the mass of the ship will stay in motion. If we are in a hurry we could use a different fuel. I mean, if we want to go all sci-fi we could use a reactor so it's fuel would be measured in it's half life.

...and I believe you're misunderstanding E=MC^2. The closer to 1c you get, the more energy you need to get to that speed. That energy comes from the fuel you use and that fuel has mass. The faster you go, the more energy you need, the more mass you have to carry to get to that speed. Essentially, you need incredible amounts of mass to have enough energy to accelerate said mass to 1c, the speed limit in Newtonian physics. All the while, you have to concurrently deal with all the stuff floating around in the "vacuum" of space that you are slamming into with ever more violent and energetic impacts, all of it eating away at your forward momentum.

28. Okay,...so you're talking deflector shield like Star Trek...

I'm not suggesting anything outside of Newtonian physics. When you get into Eisenstein physics we are talking mass increasing to infinity and time stopping.

Back to my original point. We have the ability to create a probe with the mission to travel to the nearest star and return images in our lifetime with our current technology and the Ion drive creates a continuous thrust and that is the way we would be able to achieve the high speed needed to traverse the distance between the stars.

29. The continuous thrust of an ion drive is fine when you have an external energy source

ie the Sun, in the solar system, and when the velocities you're talking about are only, say, 100,000mph (about 4.4*10^4 m/s). But an interstellar probe at 0.1c has to go 700 times faster than that, and do it where the energy from the Sun is negligible, so it has to carry that energy with it while it gradually uses it. Even with nuclear fusion in the form of the 'multiple bomb' approach in the posts above, you're looking at limits imposed by the proportion of mass that gets converted to energy - typically less than 1%. The problem is that you have to accelerate your energy source as well as your probe. Even trying this with an ion drive would require constructing a working fusion reactor to power it, but the limits from the weight of fuel still apply.

40. That was in a response to the atomic drive we were also talking about.

75. No, the fuel mass does grow exponentially, literally

Looking back over the thread, I think this is the one thing you really don't grasp. The Tsiolkovsky rocket equation is a fundamental part of rocketry, and over 100 years old. It says (better illustrated on Wikipedia, where they can write proper equations)

The maximum change in speed obtainable equals the exhaust velocity multiplied by the natural logarithm of (the initial mass of rocket including propellant, divided by the final mass of the rocket)

or, rearranging it,

minitial = mfinal * e ^ (deltaV / Vexhaust)

So, if you have a an exhaust velocity of, say, 100 km/s (compared with the Dawn one of 37 km/s, to allow for some technological improvement), and you want to reach, say, one hundredth of the speed of light - 3,000 km/s, the initial mass, with propellant, must be e ^ (3000/100) (or exp(3000/100), if you prefer that notation) times the final mass of the probe. e ^ 30 is about 10 trillion. For every kg of payload, you'd need 10 trillion kg of fuel. And that amount of fuel would need truly massive rocket engines to get any meaningful acceleration from it to get to a decent speed with centuries rather than over multiple millennia.

There are things you can do to alleviate the problem, like use multiple stages, but above all, you need to improve the exhaust velocity. And that means putting a lot more of your energy into the exhaust (since kinetic energy goes up with the square of velocity). That needs a huge energy source. Which means we end back at nuclear fusion, effectively.

76. You would have to use nuclear to power the probe anyway because you would be too far,...

....from the sun to use solar. The engines still require particles to toss out to create the thrust. Say you have two reactors, one powers the grid to accelerate the ionized particles coming from the other. I'm picturing a hyper accelerated ionized plasma.

41. What we need to do

is figure out how to reduce the mass of a craft. Using a Gravitic Field Generator, you can take a ship the size of an aircraft carrier, shrink the mass down to a few pounds, and any amount of thrust is going to be able to give it enormous speeds. Imagine a mouse wearing a jetpack designed to carry a 200 lb human, and you understand my point.

43. Higgs!

If we've truly discovered the Higg's boson and come to understand how it lends mass to matter, what you propose may one day be possible providing there is some way to neutralize or counter its force on the macro scale while maintaining atomic and molecular integrity on the quantum scale. I fear, though, that the same force that creates mass and gravity is also responsible for maintaining the integrity of atoms themselves. Such a discovery would have a great many important implications and applications. It's too early to say what might or might not be possible.

44. That's scifi and I've heard of another one where you generate gravity in front of the space craft,..

....so it's falling into the gravity well you are generating but since the gravity well is always ahead of the craft it never reaches it but it keeps trying. Say it's a 1G difference, the craft will "fall" forward at 32 feet per second per second but unlike in an atmosphere it will not achieve a terminal velocity due to air resistance so it keeps increasing in speed. We don't have the science to affect gravity or mass at this point.

48. I do. My father worked on it...

It's probably our best hope of propelling a probe through space at high enough velocities to make the trip practical... And even at the speeds capable given ion propulsion, it doesn't come to to 100,000 mph. This is sad...

49. True, but it is the first effort at continuous drive with low fuel which is the key to high speeds..

Most of our planetary probes are sent like a projectile. One burst and then a whole lot of coasting on the inertia.

DS1 was able to maintain a steady thrust over a long duration. It's drive is based on kinetic energy from polarization instead of simple chemical reactive expansion. There are scientists now who are picturing grabbing onto a comet and using it's water as the source for hyper accelerated particles over a grid similar to the DS1 engine. If the probe itself is able to harvest it's own fuel that would be even better.

51. How do you harvest fuel outside the solar system?

Or in it, for that matter, if the probe is already moving relative to the fuel? Starting from anything that is orbiting the Sun is still basically starting from standstill, in interstellar terms.

The thrust that DS1, or Dawn, achieves is very small. They work OK because they get their energy from outside, and can get it over years. Ion engines are quite inefficient in energy terms, because they give so much to their high-speed exhaust, but efficient in fuel mass terms. Carrying the energy with them, as they'd have to do if they head away from the Sun, negates their advantages.

53. That's easy, ever hear of the Oort Cloud?

It's the place where comets come from. We have no idea of how dense it is or the size of the objects but we would find out once we got there. It's possible that a second spacecraft could go there in advance and collect fuel for the probe, then when the probe arrives it would rapidly speed up and rendezvous to refill the probe's tanks.

55. What - 'rapidly speed up' with chemical rockets?

But it's still the same basic problem - anything in the Oort Cloud has very little velocity, relative to the Sun (if it had significant velocity, it would be above escape velocity at that distance). If you say the fuel is collected so far away that the kinetic energy of the Oort Cloud object is as good as enough to give it escape velocity from the solar system, then that's just the equivalent of getting it travelling at about 100,000 mph at the same distance from the Sun as the Earth is. You need to give it another 6,750,000 mph or so just to get it up to 1% of the speed of light. The gain from starting from the Oort Cloud is minuscule in comparison to the kinetic energy needed for an interstellar flight taking less than a millennium.

56. "What - 'rapidly speed up' with chemical rockets?"

I was thinking more of a one time massive boost. Then again, it could just leave a thin trail of fuel for the other ship to fly through and scoop up without slowing down.

These are just ideas assuming a large amount of fuel would be needed. It might not be the case that you need to refuel along the way. I'm also thinking an interstellar probe would be built and launched from orbit. This would allow massive inflated tanks of fuel to be filled before departure.

Project Daedalus envisions this:

There's another thing to consider, the signal once it gets there.

There might need to be a relay station or two to get the signal back to us so those would need to be dropped along the way. All this just to do a fly through to get a close look.

You would think we could send a telescope that way and get a good look before we even get there.

57. Daedalus assumes a fusion rocket, not an ion drive

"Daedalus would be propelled by a fusion rocket using pellets of deuterium/helium-3 mix that would be ignited in the reaction chamber by inertial confinement using electron beams. The electron beam system would be powered by a set of induction coils tapping energy from the plasma exhaust stream. 250 pellets would be detonated per second, and the resulting plasma would be directed by a magnetic nozzle. The computed burn-up fraction for the fusion fuels was 0.175 and 0.133 for the First & Second stages, producing exhaust velocities of 10,600 km/s and 9,210 km/s, respectively. "

Compare that theoretical system to the exhaust velocity of the Dawn spaceprobe - about 37 km/s. It's a completely different technology, and you still need 50,000 tonnes of fuel - including the very rare helium-3.

61. Solar Sails may be a viable alternative...

A very large solar sail may be able to accelerate a probe more quickly and to a higher speed than an an ion drive. I'm pretty sure I remember hearing recently that one such probe is now in the works. With a well-planned mission you can cut the fuel requirement to a very small amount as it would only need fuel to decelerate at the end of its journey and could enter orbit about one of the stars in the centauri system at fairly high speed anyway, and photon pressure from our Sun extends plenty far enough to get a lightweight probe up to nearly .5 c and then inertia can carry it the rest of the way to the Centauri system with only slight deceleration due to interstellar dust and gas. Sometimes it's better to use a massive energy source like the Sun, that's already just sitting there.

71. Ah! That's a thought....

I've always pictured some poor crew heading out at near the speed of light only to find out when they get there that there are already people waiting for them because of the invention of an FTL drive.

I've always found the time dilation interesting anyway. Lovecraft in his story "Though the Gates of the Silver Key" had a craft called a "Light Envelope" which went at near light speed so there was no need for provisions. You get in, set the course and to you the journey seems instantaneous even though hundreds, thousands, or even millions of years could have passed. All based on the distance.

Then there's the time warp thing where you go back in time as you go forward in space. Thus you arrive early. It's a way of cheating the speed limit. And of course there's folding space as seen in Dune. Subspace travel where you enter a different realm like in Stargate which also has wormholes.

Good thing it's 2012 and the world is ending so nobody has to suffer the humiliation of being wrong.

72. That's really cool.

I know that recently they've been able to up the efficiency of these engines to propel a craft at close to 200,000 mph! It takes quite awhile for the vehicle to reach that velocity, like 0 - 60 mph in a week, but the acceleration is constant. Even a small acceleration vector in a vacuum can be quite substantial over time. Just a matter of keeping the energy supply available.

74. Keep in mind this drive is small and fairly new....

...but it works. It uses a relatively tiny about of fuel for something that is running constantly and I'm sure scientists could adapt what they've learned to create a more powerful engine. If you went up to someone on the street and told them we have probes right now using ion drive zipping around the solar system they would be surprised. Our media is more likely going to cover Honey Boo Boo than anything "nerdy". Just look at how they have flat out ignored the Curiosity rover after it landed. You get the idea the ONLY reason the media mentioned it at all was because they were hoping it would fail to fit into their "government can't do anything right and wastes money" narrative.

We have the potential of being so much better than we are and sometimes you just have to ignore the crap and live like we are already there.

38. In space, no one can hear you fart.

45. Find Astronomy Fascinating

I have started watching the Science channel at night before I go to sleep when they have the astronomy shows on. I find it strangely comforting rather than thinking about all the crap that goes on down here on planet earth!